Concrete mixing machines



Nov. 6, 1962 R. P. GREEN 3,062,515

CONCRETE MIXING MACHINES Filed March 21, 1960 2 Sheets-Sheet 1 Nov.-6,1962 R. P. GREEN 3,062,515

CONCRETE MIXING MACHINES Filed March 21, 1960 2 Sheets-Sheet 2 Swmiw:

By 5am? W40 United States Patent 3,062,515 CONCRETE MIXING MACHINESRowland Percy Green, Bath, England, assignor to Stothert & Pitt,Limited, Bath, England, a company of Great Britain Filed Mar. 21, 1960,Ser. No. 16,282 Claims priority, application Great Britain Mar. 26, 19594 Claims. (Cl. 259177) This invention relates to concrete and likemixing machines having a rotary drum for eifecting the mix.

More particularly it is concerned with a concrete mixer of the type inwhich the drum is capable both of rotation and tipping simultaneously,tipping being about a horizontal axis provided by trunnion typemountings in the frame of the machine in which the drum is supported torotate.

In existing types of concrete mixers drive to the drum is usually bymeans of a bevel pinion mounted on the machine frame and concentric withthe swinging axis of the drum, this bevel pinion meshing with a bevelwheel or similar toothed ring secured to the wall of the drum.

In another method there is employed a chain and bevel. drive through thearms of the cradle and connecting with abevel wheel fast on the base ofthe mixing drum and concentric with the rotation axis.

It will be appreciated that both forms of drive transmission, becausethey have to transmit the drive through the swinging axis of the drumcradle, involve a considerable number of drive parts which are bothcostly as regards production and involve considerable maintenance whenin operation.

, According to the present invention in a concrete mixing machine of thetype having a rotary mixing drum, drive to the mixing drum is by meansof a hydraulic system having a hydraulic motor mounted on the frame inwhich the mixing drum rotates, drive from the motor being transmittedthrough a gear box to a spindle in driving connection with the mixingdrum and the motive fluid for the motor being supplied by a hydraulicpump coupled to a prime mover.

Preferably drive from the hydraulic motor to the drum is by means ofreduction gearing. Conveniently the reduction gearing comprises a wormspindle fast on the motor shaft meshing with a worm wheel fast on thespindle of the drum.

It is a further feature of the invention that the hydraulic motor andthe gear casing housing the reduction gears are constructed asindependent units so that they can be replaced without dismantling anyinternal mechanisms when in use in the field.

The invention is diagrammatically illustrated in the accompanyingdrawings in which:

FIGURE 1 is a layout of a hydraulic drive to the mixing drum of aconcrete mixer;

FIGURE 2 is a side elevation of the mixer showing the frame, mixingdrum, and a part of a jib for use in conjunction with a drag line scoopwhen loading the skip.

FIGURE 3 is a perspective view showing the drum, drum frame and motorand gear box disconnected.

Referring to FIGURE 2 of the drawings, M indicates generally the machineframe which is mounted on a four wheeled chassis F having ground wheelsW. A mixing drum D is mounted to revolve in a drum cradle C which isprovided with trunnion type mountings in the machine frame M so that thedrum D and cradle C can be tipped to discharge its contents oncompletion of mixing.

The concrete mixer of this invention is provided with a hydraulic driveincluding a motor 1 (FIGS. 1 and 3) from which drive is transmittedthrough a gear box indicated 3,062,515 Patented Nov. 6, 1962 ICCgenerally at 2, to a spindle 11 on which the mixing drum is carried,both the motor 1 and gear box 2 being supported on the mixing drumcradle C.

Pressure fluid is delivered to the motor 1 through a delivery line 3from a pump 4 driven by a prime mover 5, usually an internal combustionengine or electric motor. A return flow line 6 from the motor 1 returnsthe motor fluid to a hydraulic fluid reservoir 8 which, together withthe prime mover 5, is mounted on the machine frame M. The pump 4, whichmay be of the gear, centrifugal or piston type, draws fluid direct fromthe reservoir 8 through a suction line 9. Flexible pipe connectionsindicated generally at 10 are provided between the delivery and returnlines 3, 6 and the motor 1 so that in the event of it being necessary todisconnect the hydraulic motor, this can readily be performed bydetaching the pipes 10.

It is a futher feature of this invention that the gear box 2 togetherwith the motor 1 are detachable as separate units as can be seen fromFIGURE 3. For this purpose the gear box comprises a cylindrical shell orcasing 23 having an axial extension 12 within which the spindle 11 isrotatably mounted in suitable bearings. The drum cradleC, which is oftubular construction has a central housing 27 provided with a machinedbore to receive the gear casing extension 12.

A gear train comprising a worm Wheel 13 fast on the I spindle 11 mesheswith a worm 14, the worm shaft being detachably connected to the motorshaft, preferably by a flexible coupling 16 so that the motor and gearbox units can be separated. The drum, which is of all steelconstruction, has an internal boss 25 of cast steel, which is integralwith a base or cap 26, the latter fitting a central opening in the baseof the steel drum.

The inside of the boss 25 is splined to receive a splined extension orstub 17 on the other end of the worm wheel spindle 11 so that drive fromthe stub 17 is directly transmitted to drum D.

As can be seen from FIGURE 1, the motor casing is provided with a flange18, by which it is bolted through four bolts 19 to a flange 20 on thegear box casing 23, which is circular. This enables the motor 1 to beuncoupled from the gear box 2, following which it is .a simple matter towithdraw the gear box 2 and extension 12 with its spindle 11 byreleasing the holding screws 36, by which a radial flange on the rearend of the bearing housing 27, is secured to the gear casing 23. Thedrum 'boss is secured to the spindle 11 by a single set screw and washerindicated at 31.

By providing a hydraulic drive in accordance with this invention, it hasthe advantage that the drive unit i.e. the motor 1 and gear box 2 aretotally enclosed, which not only eliminates risk of accident both to theoperator and to the machine, but affords complete protection to ingressof dirt and abrasives, which is particularly liable to occur due to thepresence of sand when making concrete.

As compared with a drum having an external driving ring and drivingbevel, economy in space can be effected owing to the small size of thehydraulic motor; and the minimum of gearing, namely a Worm and wormwheel may be employed. This results in a smooth drive with absence ofvibration.

A hand wheel 22, together with a chain drive, is provided for moving thedrum from the mixing to the discharge position, together with anautomatic locking device consisting of a spring loaded pin to check themovement of the drum cradle at suitable positions for loading, mixing,discharging and cleaning.

A feature of the hydaulic drive is that it can be conveniently used forreversing the direction of rotation of the drum on machines designed formixing in one direction and discharging in the opposite direction. Thismethod dispenses with expensive clutches which may be subject to rapidwear and deterioration, thus increasing maintenance costs.

It will be appreciated that instead of a worm or worm Wheel reductiongearing, use could be made of an epicyclic spur gear reduction unit.

What is claimed is:

1. A concrete mixing machine comprising a machine frame, a mixing drum,a cradle supporting said drum for rotation on its axis and mounted onsaid machine frame to provide for movements of the drum to and from itsdischarge position, said cradle having a tubular bearing housing coaxialwith said drum, a gear casing having a tubular extension fitting Withinsaid bearing housing, a spindle journaled within said tubular extensionand adapted to enter into driving engagement with said drum on theattachment of said gear casing to said bearing housing, means fordetachably connecting said gear casing to said cradle, a gear traintotally enclosed within said gear casing and connected to said spindle,and motor means for driving said gear train.

2. A concrete mixing machine comprising a machine frame, a mixing drum,a cradle supporting said drum for rotation on its axis and mounted onsaid machine frame to provide for movements of the drum to and from itsdischarge position, said cradle having a tubular bearing housing coaxialwith said drum, a gear casing having a tubular extension fitting withinsaid bearing housing, a spindle journaled within said tubular extensionand adapted to enter into driving engagement with said drum on theattachment of said gear casing to said bearing housing, means fordetachably connecting said gear casing to said cradle, a gear traintotally enclosed within said gear casing and connected to said spindle,said gear train including a worm wheel connected to said spindle and aworm engaging said Worm Wheel, a motor having a housing detachablyconnected to said gear casing and provided with a drive shaft, and meansfor detachably connecting said drive shaft to said worm.

3. A concrete mixing machine comprising a machine frame, a mixing drum,a cradle supporting said drum for rotation on its axis and mounted onsaid machine frame to provide for movements of the drum to and from itsdischarge position, said cradle having a tubular bearing housing coaxialwith said drum, a gear casing having a tubular extension fitting withinsaid bearing housing, a spindle journaled within said tubular extensionand adapted to enter into driving engagement with said drum on theattachment of said gear casing to said bearing housing, means fordetachably connecting said gear casing to said cradle, a gear traintotally enclosed within said gear casing and connected to said spindle,said gear train including a worm wheel connected to said spindle and aworm engaging said worm wheel, a hydraulic motor having a housingdetachably secured to said gear casing and provided with a drive shaftdetachably connected to said worm, and means for supplying hydraulicfluid under pressure to said hydraulic motor.

4. A concrete mixing machine comprising a machine frame, a mixing drum,a cradle supporting said drum for rotation on its axis and mounted onsaid machine frame to provide for movments of the drum to and from itsdischarge position, said cradle having a tubular bearing housing coaxialwith said drum and provided at its end remote from said drum with aflange perpendicular to said drum, a gear casing seating against anddetachably secured to said flange and having a tubular extension fittingwithin said bearing housing, a spindle journaled within said tubularextension and adapted to enter into driving engagement with said drum onthe attachment of said gear casing to said flange, a gear train totallyenclosed within said gear casing and connected to said spindle, and ahydraulic motor having a drive shaft connected to said gear train andincluding a housing detachably con nected to said gear casing.

References Cited in the file of this patent UNITED STATES PATENTS1,653,341 Chilton Dec. 20, 1927 2,038,554 Edgar Apr. 28, 1936 2,284,358Baer May 26, 1942 2,563,669 Ahearn Aug. 7, 1951 2,573,296 Arant Oct. 30,1951 2,706,623 Styes Apr. 19, 1955 2,734,393 Luenberger Feb. 14, 19562,881,629 Homier Apr. 14, 1959 FOREIGN PATENTS 871,720 Germany Mar. 26,1953 603,500 Great Britain June 17, 1948

